1. Field of the Invention
The present invention relates to a method of determining a touch event in a touch detection system, and more particularly, to a method of determining a touch event in a touch detection system with the usage of initial digital operation.
2. Description of the Prior Art
In recent years, touch sensing technology advances rapidly, and many consumer electronic products such as mobile phones, GPS navigator systems, tablets, personal digital assistants (PDA) and laptops are equipped with touch sensing functions. In various electronic products, touch sensing functions are included in a display area which originally had only display functions. In other words, an original display panel is replaced by a touch panel having both display and touch sensing functions. The touch panel can generally be divided into out-cell, in-cell and on-cell touch panel according to the difference in structure of the touch panel. The out-cell touch panel is composed of an independent touch panel and a general display panel. In the in-cell and on-cell touch panel, a touch sensing device is directly disposed on inside and outside of a substrate in the display panel, respectively.
Touch sensing techniques can be classified into a resistive type, capacitive type and optical type. The capacitive type touch panels became popular gradually since they have many advantages such as high sensing accuracy, high transparency, high reaction speed and long life. In a general capacitive touch detection system, a plurality of capacitors are deployed on a touch panel or touch screen for touch detection. The conventional touch detection method requires an entire determination for determination of occurrence of touch events, locations of the touch events and touch strengths. For example, when a touch event occurs, a touch control module may perform interpolation on sensing signals from different capacitors on the touch panel, to determine the location of the touch event. In this manner, the value of each sensing signal should be obtained with a high resolution to determine the touch magnitude in each place of the touch panel, in order to achieve accurate determination. This requires longer time and larger power consumption of the touch detection system.
In addition, there are noises existing in the sensing signals, e.g., liquid crystal module (LCM) noises, and these noises may reduce the report rate of touch events. In order to achieve a preferable report rate, the conventional noise detection and error correction method always applies a powerful filter to filter out these noises. The powerful filter may possess a narrow bandwidth to pass through the desired signals, where the narrow bandwidth corresponds to long time consumption in time domain. Alternatively, the touch control module may perform complex analog operations on the sensing signals to eliminate or reduce the interferences generated by noises.
However, the above entire determinations always require complex circuit design, higher power consumption and more time expense, and thereby reduce the performance of the touch detection system. Thus, there is a need to provide a preferable solution of signal processing and operations for touch sensing signals, to enhance the performance of the touch detection system.